Zipper Slide for Double-Layer Nylon Zipper

ABSTRACT

A zipper slide so configured that the retracted design of the rear side of the bottom slide body block relative to the top slide body block provides sufficient space for allowing the inner layer of the double-layer nylon zipper to be smoothly curved when the zipper slide is cornering, reducing zipper friction resistance and prolonging the zipper lifespan; the upper guard flanges are relatively longer than the lower guard flanges so that the upper guard flanges are kept relatively closer to the center block than the lower guard flanges to shift the fulcrum forward, enabling each of integrated opposing left and right series of interlocking teeth of the double-layer nylon zipper to face toward the fulcrum and the center block when each of integrated opposing left and right series of interlocking teeth of the double-layer nylon zipper is opened to the extent.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to zipper technology and more particularly, to a zipper slide for double-layer nylon zipper, which greatly improves sliding mobility, reducing zipper sewing seam and teeth wear and prolonging zipper slide lifespan.

2. Description of the Related Art

The basic functional design of a zipper slide derives from rotating engagement between gears. The left series of teeth and right series of teeth of a zip fastener are regarded as two equal length flexible tooth bar. A zipper slide is movable by a pull tab to interlock or separate left and right series of teeth. In order to enhance protection and to prevent the occurrence of zipper split, double layer zippers are created. U.S. Pat. No. D651,129, issued to the present inventor, discloses a double layer coil zipper slider for use in a double layer zipper. A zipper slider for double layer zipper increases the distance between the opposing top and bottom slide body blocks and provides a tongue-shaped guide plate at the center block between the opposing top and bottom slide body blocks for separating the upper and lower fabric tapes of the double-layer nylon zipper. According to conventional designs, the top and bottom slide body blocks are identical in shape; the top slide body block has a crown located at a top side thereof for securing a pull tab. The upper and lower layers of left and right series of interlocking teeth of a double layer zipper are fastened together with stitches.

Further, the upper layer of left and right series of interlocking teeth and the lower layer of left and right series of interlocking teeth are differently curbed when the zipper slider is cornering, causing the interlocking teeth of the lower layer of left and right series of interlocking teeth to be abnormally squeezed. Because the upper and lower layers of left and right series of interlocking teeth are moved in the same chamber in the zipper slider between the opposing top and bottom slide body blocks and differently curved when cornering, a large friction resistance can occur, and thus the stitches of the zipper can be worn out quickly, and the top and bottom slide body blocks, the center block and/or the pull tab can be easily permanently deformed or damaged.

SUMMARY OF THE INVENTION

The present invention has been accomplished under the circumstances in view. It is the main object of the present invention to provide a zipper slide for double-layer nylon zipper, which has the characteristics of good security performance, long lifespan and high linking strength, and can easily be opened and closed when cornering.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a front elevational view of a zipper slide for double-layer nylon zipper in accordance with the present invention.

FIG. 2 is a top view of the zipper slide for double-layer nylon zipper in accordance with the present invention.

FIG. 3 is a bottom view of the zipper slide for double-layer nylon zipper in accordance with the present invention.

FIG. 4 is a left side view of FIG. 1.

FIG. 5 is a right side view of FIG. 1.

FIG. 6 is a sectional view taken along line A-A of FIG. 1.

FIG. 7 is a sectional view taken along line B-B of FIG. 1.

FIG. 8 is an oblique top elevational view of the zipper slide for double-layer nylon zipper in accordance with the present invention.

FIG. 9 is a sectional elevation corresponds to FIG. 7.

FIG. 10 is a schematic drawing illustrating a corning status during operation of the zipper slide for double-layer nylon zipper in accordance with the present invention.

FIG. 11 is a right side view of FIG. 10.

FIG. 12 is a schematic sectional view illustrating an operating status of the zipper slide for double-layer nylon zipper in accordance with the present invention.

FIG. 13 is a schematic sectional view illustrating an operating status of a zipper slide for double-layer nylon zipper according to the prior art.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 1-9, a zipper slide 60 for double-layer nylon zipper in accordance with the present invention is shown. As illustrated, the zipper slide 60 comprises a top slide body block 1, a bottom slide body block 2, two upper guard flanges 3 respectively downwardly extended from two opposite lateral sides of the top slide body block 1, two lower guard flanges 4 respectively upwardly extended from two opposite lateral sides of the bottom slide body block 2, a center block 5 connected between the top slide body block 1 and the bottom slide body block 2, a tongue-shaped guide plate 7 forwardly extended from a front middle part of the center block 5 and equally spaced between the top slide body block 1 and the bottom slide body block 2 for separating the upper and lower fabric tapes of the double-layer nylon zipper 6, two upper guide grooves 9 located on a rear part of a bottom surface of the top slide body block 1 at two opposite lateral sides relative to the center block 5, and two lower guide grooves 10 located on a rear part of a top surface of the bottom slide body block 2 at two opposite lateral sides relative to the center block 5. The top slide body block 1 and the bottom slide body block 2 have respective front sides thereof kept in vertical alignment. The bottom slide body block 2 has its rear side retracted relative to the rear side of the top slide body block 2. The retraction distance is about equal to the thickness S of one layer of zipper chain tape of the double-layer nylon zipper 6 (see FIG. 3, FIG. 7 and FIG. 10). The zipper slide 60 further comprises a connection part 8 connected between the rear side of the bottom slide body block 2 and a bottom side of the center block 5 and kept in flush with the bottom slide body block 2 to reinforce the tensile strength of the top slide body block 1 and the bottom slide body block 2. Further, the upper guard flanges 3 are relatively longer than the lower guard flanges 4 so that the upper guard flanges 3 are kept relatively closer to the center block 5 than the lower guard flanges 4 to shift the fulcrum G forward (see FIG. 12), enabling each of the integrated opposing left and right series of interlocking teeth 61 to face toward the fulcrum G and the center block 5 (tooth engagement position H) when it is opened to the extent. As the fulcrum G has been shifted forward, each of the left and right series of interlocking teeth 61 can quickly return to the normal tooth pitch b when reached the tooth engagement position H. In the prior art design shown in FIG. 13, the length of the upper guard flanges 3′ of the zipper slide 60′ remains the same as the lower guard flanges, and therefore this design cannot shift the fulcrum G′ forward. In consequence, each of the left and right series of interlocking teeth 61′ can quickly return to the normal tooth pitch when reached the tooth engagement position, leading to engagement failure or disengagement. In comparison to the prior art design, the tooth pitch b (see FIG. 12) of the present invention is smaller than the tooth pitch a (see FIG. 13) of the prior art design, and therefore, the invention enhances tooth engagement stability, preventing accidental sliding or twisting of the zipper slide relative to the double-layer nylon zipper 6. Further, the design of the upper guide grooves 9 at the top slide body block 1 around the center block 5 and the lower guide grooves 10 at the bottom slide body block 2 around the center block 5 facilitates coupling the zipper slide 60 to the double-layer nylon zipper 6. Further, the width E of the entrance of each of the upper guide grooves 9 and lower guide grooves 10 is equal to the width of the interlocking teeth; the depth of the upper guide grooves 9 and lower guide grooves 10 is in the range about ⅛˜¼ of the thickness S of the interlocking teeth (i.e., ⅛ S˜¼ S).

Subject to the retracted design of the rear side of the bottom slide body block 2 relative to the top slide body block 1, there is sufficient space for allowing the inner layer of the double-layer nylon zipper 6 to be smoothly curved when the zipper slide is cornering, reducing zipper friction resistance and prolonging the zipper lifespan.

Further, the design of the connection part 8 at the rear side of the bottom slide body block 2 around the center block 5 greatly enhances the connection strength between the bottom slide body block 2 around the center block 5 and the tensile strength between the top slide body block 1 and the bottom slide body block 2. Further, when moving the zipper slide 60 to close or open the left and right series of interlocking teeth 61 of the double-layer nylon zipper 6, the left and right series of interlocking teeth 61 are positively supported on the connection part 8 and kept within a limited angle F (see FIG. 11), and thus, the left and right series of interlocking teeth 61 can be smoothly and positively guided by the zipper slide 60 into an interlocked status.

In conclusion, the zipper slide 60 for double-layer nylon zipper in accordance with the present invention is characterized by the retracted design of the rear side of the bottom slide body block 2 relative to the top slide body block 1 to provide sufficient space for allowing the inner layer of the double-layer nylon zipper 6 to be smoothly curved when the zipper slide is cornering, reducing zipper friction resistance and prolonging the zipper lifespan; the design of the connection part 8 at the rear side of the bottom slide body block 2 around the center block 5 greatly enhances the connection strength between the bottom slide body block 2 around the center block 5 and the tensile strength between the top slide body block 1 and the bottom slide body block 2, enabling the left and right series of interlocking teeth 61 to be positively supported on the connection part 8 so that the left and right series of interlocking teeth 61 can be smoothly and positively guided by the zipper slide 60 into an interlocked status when the zipper slide 60 is cornering.

While only few embodiment of the present invention have been shown and described, it will be understood that various modifications and changes could be made thereunto without departing from the spirit and scope of the invention disclosed. 

What is claimed is:
 1. A zipper slide used in double-layer nylon zipper, comprising a top slide body block having opposite front and rear sides, a bottom slide body block having opposing front and rear sides, two upper guard flanges respectively downwardly extended from two opposite lateral sides of said top slide body block, two lower guard flanges respectively upwardly extended from two opposite lateral sides of said bottom slide body block, a center block connected between said top slide body block and said bottom slide body block, and a tongue-shaped guide plate forwardly extended from a front middle part of said center block and equally spaced between said top slide body block and said bottom slide body block for separating upper and lower fabric tapes of the double-layer nylon zipper, wherein: the front sides of said top slide body block and said bottom slide body block are kept in vertical alignment, the rear side of said bottom slide body block is retracted relative to the rear side of said top slide body block, and the retraction distance is about equal to the thickness of one layer of zipper chain tape thickness of the double-layer nylon zipper; the zipper slide further comprises a connection part connected between the rear side of said bottom slide body block and a bottom side of said center block to reinforce the tensile strength of said top slide body block and said bottom slide body block.
 2. The zipper slide used in double-layer nylon zipper as claimed in claim 1, wherein said upper guard flanges are relatively longer than said lower guard flanges so that said upper guard flanges are kept relatively closer to said center block than said lower guard flanges to shift the fulcrum forward, enabling each of integrated opposing left and right series of interlocking teeth of the double-layer nylon zipper to face toward said fulcrum and said center block when each of integrated opposing left and right series of interlocking teeth of the double-layer nylon zipper is opened to the extent.
 3. The zipper slide used in double-layer nylon zipper as claimed in claim 1, wherein the zipper slide further comprises two upper guide grooves located on a rear part of a bottom surface of said top slide body block at two opposite lateral sides relative to said center block, and two lower guide grooves located on a rear part of a top surface of said bottom slide body block at two opposite lateral sides relative to said center block.
 4. The zipper slide used in double-layer nylon zipper as claimed in claim 3, wherein said upper guide grooves and said lower guide grooves each have an entrance at an outer side thereof, said entrance having a width equal to the width of the interlocking teeth and a depth in the range about ⅛˜¼ of the thickness of integrated opposing left and right series of interlocking teeth of the double-layer nylon zipper. 